How high can a fly fly?
Eleanor Drinkwater answered listener Alex's question about how high a fly can fly...
Eleanor - If you think about the kinds of things that high altitude might affect an animal or particularly a fly, kinds of things that spring to mind are low oxygen levels, temperature - so particularly small insects find it difficult to thermoregulate so the temperature might be a big one. The higher you go, essentially the harder an insect would have to work in order to be able to keep flying.
I don't know whether or not the tallest building in the world would be tall enough to cause a fly any problems. That might depend on the fly. But there are some insects that it would definitely be no problem at all for.
You get some bumblebees that are incredibly well adapted in order to live particularly at high altitudes, and they do forage in the mountains. But when they took them into the lab to test just how high they could fly, they changed the air pressure to the equivalent of around about 9,000 metres, which is taller than the height of Everest, which is just quite extraordinary!
Remarkably, they found that they were totally fine and all they did was they shifted the way that they flew. So they didn't flap more because that would be un-energy efficient. Instead they kind of drew a wider arc with their wing in order to give themselves more lift, which they reckon is probably an adaptation which they've developed to allow themselves to carry lots of pollen and nectar. But actually it's also a really useful way of being able to deal with high altitudes as well. So if it's the alpine bumblebee, it definitely wouldn't be a problem at all.